I don't want to stir up controversy with this post. I am NOT in favor of using oil. Please understand this. I want an honest answer to this question. I've read Dr. McDougall's answer and wasn't satisfied. It seemed to brush the findings aside. I am hoping you can shed more light on this subject, Jeff.

There was a study done and published in 2004 (Am.J.Clin.Nutr. 2004, Aug80(2);396-403). Carotenoid bioavailability is higher from salads ingested with full-fat than fat-reduced salad dressings as measured with electrochemical detection. It showed clearly that the full-fat salad dressing containing 28 g canola oil (that's 280 calories from fat) showed substantially greater absorption than even the lower fat salad dressing that had only 6 g of fat from canola oil versus almost NO absorption with the no fat salad dressing used.

I know all the reasons why fat is bad (including the popular olive oil). If this is true and I don't see how to refute it, can we then conclude that if we want to absorb all these nutrients we should AT LEAST add some avocado, some nuts or tofu dressings?

And I've read elsewhere (sorry I don't have that on hand) that in order absorb Vitamin E, Vitamin D and I think Vitamin K we all need fat in our diet. Yes, I know you will say there is some fat in most foods, including lettuce, but it certainly wasn't enough in this case, i.e. salads, which also included raw carrots. So is the answer to cook everything? Even lettuce? Or blending them? Please do not think I'm trying to be contentious.

Suebee wrote:I don't want to stir up controversy with this post. I am NOT in favor of using oil. Please understand this. I want an honest answer to this question. I've read Dr. McDougall's answer and wasn't satisfied. It seemed to brush the findings aside. I am hoping you can shed more light on this subject, Jeff.

There was a study done and published in 2004 (Am.J.Clin.Nutr. 2004, Aug80(2);396-403). Carotenoid bioavailability is higher from salads ingested with full-fat than fat-reduced salad dressings as measured with electrochemical detection. It showed clearly that the full-fat salad dressing containing 28 g canola oil (that's 280 calories from fat) showed substantially greater absorption than even the lower fat salad dressing that had only 6 g of fat from canola oil versus almost NO absorption with the no fat salad dressing used.

I know all the reasons why fat is bad (including the popular olive oil). If this is true and I don't see how to refute it, can we then conclude that if we want to absorb all these nutrients we should AT LEAST add some avocado, some nuts or tofu dressings?

And I've read elsewhere (sorry I don't have that on hand) that in order absorb Vitamin E, Vitamin D and I think Vitamin K we all need fat in our diet. Yes, I know you will say there is some fat in most foods, including lettuce, but it certainly wasn't enough in this case, i.e. salads, which also included raw carrots. So is the answer to cook everything? Even lettuce? Or blending them? Please do not think I'm trying to be contentious.

Thank you very much..

Hi Sue

I am always amazed at the studies that get so much attention and are always used to endorse or defend or to rationalize unhealthy habits. And, the marketers and advertisers are sure to get right behind them and keep these studies in the news.

This is one of them

We just never see people put this same effort and attention into, or try to defend, the studies than regularly come out supporting good healthy habits. Imagine if this much effort and energy was put into eating more fruits and vegetables every day, which are continually shown to be the healthiest change people can make.

But, anyway....

First off, you absorb plenty of nutrients from the food you eat. The main reason the typical person is lacking in nutrients is not because they don't add enough oil, but because they eat a highly refined and processed junk food diet , do not eat enough unrefined plant foods, and do not chew their food properly. In fact, most people already add to much oil to their diet and they still are nutrient deficient.

Many studies, other than this one, have shown humans absorb the nutrients and phtyochemicals in foods just fine. For instance, this is how the ORAC scale was developed. If this was really true, that without oil, you absorb no nutrients, there would be a major health campaign about it and I for one, would be pouring oil all over my foods. BTW, I use not oil, and have had my carotenoid levels checked and they are out the roof. Amazing.

Second, oil is a relatively new phenomenon in human history, Relatively speaking, it is only recently we figured out how to extract oil from foods, stabilize it and use it in the food supply. So, somehow, humans have been able to absorb the nutrients from the foods they have eaten for centuries. We also know of many native cultures that still live on traditional diets that are less than 8% fat, and do not use oil, and have excellent health and very low disease rates.

Third, the math is misleading.

If you want to beleive what they say, you would then have to look at the total absorption per calories as the oil may increase absorption rates, but it also adds LOTS of calories lowering the overall nutrient density.

Lets say you have one medium tomato, which is 20 calories. And you measure, the absorption. Then you add a TB of oil, which is 120 calories

And it increases absorption. It would have to increase absorption over 600% to matter. Why? Because for the same 120 calories, I could have eaten 6 more tomatoes.

The olive oil would have supplied virtually no other nutrients, other than a few phystosterols and a little vitamin E (1.9 mgs) some vit K (8.1 mcgs) and virtually no minerals . It would have added no fiber, and it would have added almost 2 grams of saturated fat.

Now, on the other hand, adding in the 6 tomatoes (for the same 120 calories) would have increased the amount available to us of every single nutrient 6x. In other words, the 6 tomatoes added in

In the study, they used 2 TB of olive oil, so we have to double all numbers, which only makes the tomatoes look even better.

Which do you think is healthier for you from an overall picture? Adding two TB of oil, or eating 240 calories of more tomatoes (or other vegetables)? Adding in 3.6 grams of saturated fat from the olive oil, or adding in 16 more grams of fiber from the tomatoes? Increasing the percent absorption of 3992 mcgs of carotenoids (that is in the original one tomato), or adding in 53,000 mcgs (from the additional tomatoes)?

I am going for the tomatoes!

In HealthJeff Novick, MS, RD

PS Tomatoes are around 8% fat. Romaine lettuce is around 15% fat, strawberries are around 9%.

Thank you Jeff for your timely answer. So you are saying that even if I might not absorb the phytonutrients from the lettuce or much from raw carrots, the bulk of my already good diet would make up the difference. From my readings of other cultures, they tend not to each much raw green vegetables. Even the Chinese stir fry them (and yes, they do use oil! using the rapeseed oils--which then gives them lung cancer) or other cultures use animal fats. I don't know of too many cultures that use NO added fats to their vegetables. I already eat plenty of raw fruits, cooked vegetables. I was just wondering about the raw greens themselves. And yes, I'm already aware of the studies done that show absorption of nutrients is increased when tomatoes are cooked. I haven't used this single study as an excuse to use oil. But it did introduce nagging doubts.

Suebee,
Yes, there are lots of raw green veggies in the diet in other cultures. At least, I know for sure that in China, Japan, Korea at the very least that brined vegetables are very popular (sauerkraut-type) and these are prepared raw. If you read books about pickling, you'll hear theories that the pickling process increases their nutritional value, but I don't know if this is true. (It does add a lot of sodium.) This is a tradition that is very old and is also current. A Chinese friend lived with us for a year or so. Since we took turns cooking, we got to experience home-style chinese cooking (not like restaurant food at all). A preserved vegetable sort of like mustard greens was frequently part of the meal she prepared. Korean friends often give us a jar of kimchee (just like grandma used to make), which as long as it doesn't have fish in it is just raw veggies (Bok choi and various others) and really delicious. I could eat a whole jar at one sitting! In fact, Koreans are known to eat large quantities of the stuff--something like a half-pound per day per person on average! Most of this is made at home with raw veggies. Purchased, canned kimchee tastes nothing like it. I have both Japanese and Vietnamese recipes that include raw vegetables, often shredded and wrapped to dip. Bean sprouts are really a green vegetable, and these are mostly eaten raw (though certain kinds are steamed lightly). In general in Asian cooking, vegetables are cooked quickly and lightly (either in oil or steamed) so they are often still crunchy.

I have no idea if people in these cultures eat non-brined raw vegetables in season, but I wouldn't assume either way--maybe they do! There are a lot of assumptions made sometimes not based on actual experience on the ground. Possibly access to gardens, transport facilities and refrigeration or lack thereof would play a role.

How could I forget pickled vegetables? I tried macrobiotics a long time ago, so yes, I was familiar with that tradition (stemming back to Japan) and I've eaten kimchee also. And I have a Chinese neighbor who showed me from her refrigerator a great variety of pickled greens, seaweeds, etc. And this method of preparing food does add necessary probiotics to their diet and enzymes which help with digestion of a heavily grained diet (rice) BUT it also increases their rates of stomach cancer. So that might not be much of a tradeoff AND it dramatically increases blood pressure (my Chinese neighbor for instance who still uses these products and takes blood pressure medication!). It's also a well-known cause in Japan. I'm still wondering about the raw salad business and how to absorb the nutrients. Can't say I am a fan of salads without some fat, so for now, I'm blending the greens with fruit. I wondered what Jeff thought, that's all.

Suebee wrote: So you are saying that even if I might not absorb the phytonutrients from the lettuce or much from raw carrots, the bulk of my already good diet would make up the difference.

Not exactly.

What I am saying is that if they want to do the experiment and do it correctly, then they need to add in a third group, which is one that increased the amount of the vegetable in an amount to equal the calories they added from the fat, and then compared the absolute intake for all three groups. One group just vegetables. Second group vegetables plus "x" calories from oil. Third group vegetables, plus more vegetables to equal the "x" calories. Then compare the difference between group 2 and 3 and not just group 2 and 1.

Again, though, this is missing the main issue. More is not always better. Absorption of protein is slightly better from animal foods, so is that a rationale to eat animal foods? If we just want to get the highest absorption, then IV nutrients may be the solution as they are often absorbed better than any food. Forget adding oil, let us all just take a shot everyday of IV nutrients, anti-oxidants and phyto-chemicals.

What I am saying is that a unrefined plant based whole food diet, made up of a variety of foods from the known healthy food groups, will supply you with the adequate amount of nutrients you need. And, baring any major digestive health issue, if you chew your food properly, and have a variety of foods with some lightly cooked and some chopped , etc etc, you will absorb the amounts you need.

Proving that I can manipulate the food in some way so you absorb more of a single nutrient or of a few nutrients is irrelevant unless you can prove that somehow that is going to result in better health and/or longer life. They have never done that.

We have to look at the total picture and this is why I recommend we focus on foods and not isolated nutrients and why in the above experiment, the group i created, with the extra tomatoes, has the best "overall" nutritional package.

Suebee wrote: From my readings of other cultures, they tend not to each much raw green vegetables. Even the Chinese stir fry them (and yes, they do use oil! using the rapeseed oils--which then gives them lung cancer) or other cultures use animal fats. I don't know of too many cultures that use NO added fats to their vegetables.

I do not see the obsession in this culture with "added" fats. As I pointed out, everything we eat has naturally occurring fat in it, and some plant foods much more than you think. I gave 3 examples. Oatmeal is 16% fat.

The Chinese may use some added oil to stiry fry in, but it is not a lot and their total fat is still low. But, that is still missing the point.

The Okinawans, back in the 50s before they got westernized (who are now the longest lived population with more people over 100 then anywhere else) ate a diet that was around 9% fat with no added oils. So do the Taramhumara and Pima Indians in the Sierra Madre mountains of Mexico as did the original Hawaiians. All these diets were less than 10% fat and they were all known for their health. This info is published in mainstream medical journals. And, when we re-create these diets and put people on them today, they experience dramatic improvements in their health, very quickly.

In Health
Jeff Novick, MS, RD

Last edited by JeffN on Fri Mar 07, 2008 2:33 pm, edited 1 time in total.

Suebee wrote:I'm still wondering about the raw salad business and how to absorb the nutrients.

Chop, Slice, Dice, and Mix. Then, Chew thoroughly.

Suebee wrote: I wondered what Jeff thought, that's all.

I think you should eat your veggies in salads, soups, stews, etc. Added fat is not required.

PS, be careful of overdoing pickled vegetables. This is a warning even from the cancer societies as the incidence of stomach cancer is still high in the areas of the world that have the highest intakes of pickled/fermented vegetables, probably from the high salt intake.

Thank you very much for further clarification, Jeff. You are a wonderful addition to the McDougall team. And I only bring up the "culture issue" because Dr. McDougall does over and over--especially in talking about starch-based diets as the one the world has run on--except of course Eskimos. And no, I wasn't advocating pickled vegetables, although you probably added that for the benefit of the other poster. I don't eat them anymore. And my question about salads was personal because I do have digestion issues and my teeth don't work all that well (and no, aside from major surgery there is nothing I can do about it).

Excellent response. You are a real asset to the board. How do you find the time to be so active here and on your own site and on the speaking circuit? Maybe its the occasional "pat on the back" that keeps you going. Keep it up!

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